1. Field of the Invention
The field of the invention is that of electromagnetically actuated devices and more particularly actuators or motors of this type which are capable of both linear and rotary drive. The field of the invention is particularly or especially that of combined linear and rotary steppers or stepper motors.
2. Description of the Prior Art
Rotary stepper motors are widely known and used in various technical fields. The common form of such a stepper motor is one that operates in 200 discrete steps, the motor having a toothed motor and a stator with poles constructed appropriately for this number of steps. Examples of rotary stepper motors are in U.S. Patents such as U.S. Pat. Nos. 2,931.929; 2,982,872, and 3,434,014. Stepper motors that operate in steps are commonly used in connection with digital equipement wherein pulses are applied to the stepper motor which is used as an actuator.
Linear electromagnetic actuators are also known in the art, such devices embodying linearly movable armature members having teeth which are associated with a stator having poles and windings which are energizable to cause the movable member to move in the direction of its length. An example of such a device is illustrated in U.S. Pat. No. 3,894,275.
Devices are known in the prior which are combined rotary and linear motors or positioning mechanisms. Illustrative of such devices are the following U.S. Pat. Nos.: 3,394,295; 3,430,120; 3,441,819; 3,745,433; 3,851,196; and 3,889,165. The latter patent utilizes a cylindrical movable member which has teeth both on the inside and the outside associated with stators having windings so arranged as to produce both linear and rotary movement.
All of the prior art teachings referred to are lacking in the particular constructional improvements of the invention described in detail hereinafter. The prior art devices are lacking in specific effectiveness, capabilities, simplicity and compactness of constructional arrangements whereby to realize efficiency and effectiveness of both the linear and rotary movements. The nature of the improvements is brought out more clearly in the detailed description hereinafter of the preferred embodiment.